Good work! You learned something with all that sweat and effort! I think my CL has some LED replacement bulbs in the headlights. They work fine but I get a whole bunch of warning messages on the instrument cluster. Might be some in the taillights as well. I haven’t chased them down yet since everything works but the nannies are Not Happy.
I guess newer cars have LEDs so the new replacements will work straightaway but I wonder why there are no adaptations from the bulb manufacturers for backwards compatibility. --FT Sent from iFōn > On Aug 13, 2022, at 4:57 PM, dan penoff.com via Mercedes > <[email protected]> wrote: > > Kudos to Jim for confirming the pull up voltage theory! > > I believe there has been a comedy of errors that led to this situation: > > 1.) The voltage at the 7 pin socket is a “pull up” voltage from the SAM and > won’t carry any current to speak of. > > 2.) This voltage, while minimal, was enough to light the LEDs in the adapter > socket, which would explain why they were lit for the turn signals when the > signals weren’t on. > > 3.) The UHaul trailer, despite what the lot guy told me, almost certainly had > LED lights. > > 4.) The circuitry in the SAM has “lights out” functionality much like it does > for any other light on the body. This means it wouldn’t have played nice with > LEDs in the circuit unless there was a load resistor somewhere. > > How did I confirm? > > A tried and true and quite antiquated approach - an 1157 bulb as a test > light. When connected to the appropriate terminal on the 7 pin socket, would > light up and perform as expected for turn signal, brake light or running > lights. > > So I burned maybe 90 minutes and five pounds of sweat chasing this down, but > now I have a better understanding of the system and discovered the location > of a number of different components on the car. And I got a full diagnostic > scan on it as well, showing almost 100% check marks, which is always nice. > > I finished my time up with a good Martha’ing on the interior with the shop > vac, and even found a little bit of cruft in the cowl vents I had missed that > has now been vacuumed out. > > Lesson learned. I need to find an adapter that will allow the use of LEDs in > the trailer harness. Time to play inside for the rest of the day and enjoy > the AC. > > -D > >> On Aug 13, 2022, at 4:10 PM, Kaleb Striplin via Mercedes >> <[email protected]> wrote: >> >> The u haul trailer we rented a while back was all LED. Everyone I have seen >> for a long time has been. Even with that it worked fine with our GL. I’m >> wondering if someone installed the resistors or whatever is needed on mine >> to make it work. >> >> Sent from my iPhone >> >>>> On Aug 13, 2022, at 2:40 PM, dan penoff.com via Mercedes >>>> <[email protected]> wrote: >>> >>> Thanks for the insight, Jim, I was wondering this as well since the SAM >>> drives it directly. However, when it was plugged into a “real” trailer we >>> still got nothing. >>> >>> I’ve got an 1157 lamp with some leads soldered to it - I’m going to try >>> that on each terminal and see what happens. >>> >>> Everything else has checked out. Now I’m wondering if the UHaul trailer >>> *did* have LED lamps, as these do not work with this system for the same >>> reason as above. I asked the UHaul guys if the trailer lamps were LEDs and >>> they said no. Hmm. That would also explain why the diagnostic LEDs were lit >>> on the adapter - it would only take a a few mA to drive them. >>> >>> More as I know it. >>> >>> -D >>> >>>>> On Aug 13, 2022, at 3:07 PM, Jim Cathey <[email protected]> wrote: >>>>> >>>>> And there is still power to all terminals at the 7 pin socket (except for >>>>> trailer brake and ground.) >>>> >>>> Power? Or +12V measured with a multi-megohm input impedance meter? >>>> (Zero current, essentially.) Chances are it's got a pullup system, >>>> looking for >>>> the load of bulbs to draw signals to ground so that the car can do lamp-out >>>> checking, and trailer-plugged-in checking, etc. >>>> >>>> -- Jim >>>> >>> >>> _______________________________________ >>> http://www.okiebenz.com >>> >>> To search list archives http://www.okiebenz.com/archive/ >>> >>> To Unsubscribe or change delivery options go to: >>> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >>> >> >> >> _______________________________________ >> http://www.okiebenz.com >> >> To search list archives http://www.okiebenz.com/archive/ >> >> To Unsubscribe or change delivery options go to: >> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com >> > > _______________________________________ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
